The present invention is directed generally to apparatus for termination and distribution of telephone or like communication lines, and more particularly to a modular system for such termination and distribution. This modular system may terminate different numbers of line pairs and be constructed to serve as a main entrance or interface terminal, as a riser terminal, or as a distribution terminal.
In relatively large telephone or other communication lines installations, for example in large buildings, different types of termination assemblies are required for terminating and distributing lines throughout the building. For example, a main entrance terminal is required to receive telephone lines entering the building and to distribute these lines among different portions, or to different floors, of the building. Such distribution is initially accomplished by riser cables leaving the main entrance terminal and running to the other floors or areas. These riser cables are commonly fed to riser terminals, which terminate the riser cables for distribution on a particular building floor, and feed additional riser cables to further floors. The distribution of lines on each floor is handled by one or more distribution terminals, which provide terminating facilities for key telephone service, station or other communication lines fed by distribution cables from the riser terminal. Yet other types of termination assemblies, generally known as interface terminals, may terminate both outside lines and station lines.
Prior art arrangements include backboards having a number of brackets mounted thereon for accepting predetermined numbers and configurations of terminal blocks. These terminal blocks mount a plurality of electrically conductive terminals for receiving wires or conductors to be terminated thereon. Generally, the number of lines which may be terminated on such an assembly depends upon the number and configuration of the terminals carried on the terminal blocks mounted on the backboard brackets. When terminal blocks have been mounted on a backboard, the structure is generally referred to as a "field." In typical installations, then, various combinations of fields form either a riser terminal, a distribution terminal, a main entrance terminal or an interface terminal, as required. The numbers and configurations of fields utilized in each of these terminals is different, requiring some degree of skill of the workman or installer, in addition to reference to installation manuals and instructions, for the proper assembly of the terminal structure from the components available. Once the required fields have been assembled by mounting appropriate terminal blocks on the appropriate backboards, the lines to be terminated at the terminal structure must be individually attached to the appropriate terminals. This procedure is also relatively complex and time consuming, as many as several hundred line pairs being accommodated in a typical terminal structure. Moreover, connections must generally be made with both the front and back sides of the terminals on the terminal blocks. Additionally, a plurality of jumper wires are generally required between the front sides of terminals of the different fields. It will be appreciated, that in the course such complex wiring there is considerable opportunity for error.
Accordingly, one known prior art structure has been proposed to eliminate some of the wiring to be performed by the installer, by providing conventional connectorized cables prewired to carry the desired number of telephone lines. Mating connectors for receiving these cables are mounted on the backboard of a field and prewired to the back sides of the terminals of the field. This arrangement relieves the installer or workman from manually terminating approximately one half of the wires in the field, that is, those wires running from the cable to the back sides of the terminals.
Another problem in the construction and assembly of such large terminals is the effective utilization of available space in a building, to accommodate such a structure. For example, closets or cabinets are generally provided for such installations, and as such offer only a limited space to accommodate a terminal structure. Moreover, the terminal structures of the prior art are generally of limited height or vertical extent, commonly only permitting a maximum of three backboards or field assemblies to be mounted vertically. A significant limitation in this regard lies in the number of jumper wires between the various fields which may be conveniently and relatively neatly run and cabled in the prior art structures. These structures, it should be noted, mount all of these terminal blocks in a generally vertical orientation, requiring the majority of jumper wires to be cabled and run generally vertically. Accordingly, should additional field assemblies be required to accommodate additional telephone equipment in an existing assembly, these fields must be added to the sides of the existing structure. In view of relatively limited installation space such additional space to the sides of a terminal may not be available in many installations. However, in a typical building installation considerable vertical space is generally available between floor and ceiling of the building. But the vertical orientation of prior art structures makes vertical mounting of additional fields difficult or impossible.
All of the above considerations present significant problems to the telephone installer and invite both inefficiency and error in constructing and assembling relatively large terminal installations.